So first check to see if the app-all.js file actually has content, or rather all of the content that it should have based on the included files. It could be that the build worked, but the execution of the build doesn't work, which is my current issue as well.

I checked the app-all.js file. There is a lot of code in it, but I can't find any of my code in there. I guess it is because of the minification. I'm just trying to make this statement come true,
"Our new SDK Tools have the power to automatically create an optimized build of your app, removing any unused classes and providing you the best loading experience possible. Along with other Optimize your Ext JS projects with our command line interface that works on any platform: Windows, Mac and Linux. Find out more about JSBuilder."

I would really like this to work and I don't really want my code exposed and a long load time when I release the project. So help from anywhere is greatly appreciated.